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901.
Oduro Appiah Joseph Agyemang-Duah Williams Fordjour Audrey Amponsah Adei Dina 《GeoJournal》2022,87(1):333-347
GeoJournal - Poor older people surviving under the Livelihood Empowerment Against Poverty (LEAP) programme continue to experience financial difficulties to formal healthcare utilisation despite the... 相似文献
902.
Hydrogeology Journal - The water-level drawdown in pumping wells is the sum of two components: aquifer loss and well loss. The latter results from mostly turbulent and nonlaminar flow in and around... 相似文献
903.
Mudimu George T. Zuo Ting Shah Ashfaq Ahmad Nalwimba Nkumbu Ado Abdou Matsalabi 《GeoJournal》2021,86(6):2927-2943
GeoJournal - Despite the Zimbabwean State’s narrative and discourse that in fast track land reform areas ‘land leasing is illegal’, there is a surge in land leasing. This article... 相似文献
904.
Stelios P. Mertikas Antonis Daskalakis Ilias N. Tziavos George Vergos Xenofon Fratzis Achilleas Tripolitsiotis 《Marine Geodesy》2015,38(3):249-259
This work presents the first calibration results for the SARAL/AltiKa altimetric mission using the Gavdos permanent calibration facilities. The results cover one year of altimetric observations from April 2013 to March 2014 and include 11 calibration values for the altimeter bias. The reference ascending orbit No. 571 of SARAL/AltiKa has been used for this altimeter assessment. This satellite pass is coming from south and nears Gavdos, where it finally passes through its west coastal tip, only 6 km off the main calibration location. The selected calibration regions in the south sea of Gavdos range from about 8 km to 20 km south off the point of closest approach. Several reference surfaces have been chosen for this altimeter evaluation based on gravimetric, but detailed regional geoid, as well as combination of it with other altimetric models.Based on these observations and the gravimetric geoid model, the altimeter bias for the SARAL/AltiKa is determined as mean value of ?46mm ±10mm, and a median of ?42 mm ±10 mm, using GDR-T data at 40 Hz rate. A preliminary cross-over analysis of the sea surface heights at a location south of Gavdos showed that SARAL/AltiKa measure less than Jason-2 by 4.6 cm. These bias values are consistent with those provided by Corsica, Harvest, and Karavatti Cal/Val sites. The wet troposphere and the ionosphere delay values of satellite altimetric measurements are also compared against in-situ observations (?5 mm difference in wet troposphere and almost the same for the ionosphere) determined by a local array of permanent GNSS receivers, and meteorological sensors. 相似文献
905.
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907.
George Panteras Sarah Wise Xu Lu Arie Croitoru Andrew Crooks Anthony Stefanidis 《Transactions in GIS》2015,19(5):694-715
The analysis of social media content for the extraction of geospatial information and event‐related knowledge has recently received substantial attention. In this article we present an approach that leverages the complementary nature of social multimedia content by utilizing heterogeneous sources of social media feeds to assess the impact area of a natural disaster. More specifically, we introduce a novel social multimedia triangulation process that uses both Twitter and Flickr content in an integrated two‐step process: Twitter content is used to identify toponym references associated with a disaster; this information is then used to provide approximate orientation for the associated Flickr imagery, allowing us to delineate the impact area as the overlap of multiple view footprints. In this approach, we practically crowdsource approximate orientations from Twitter content and use this information to orient Flickr imagery accordingly and identify the impact area through viewshed analysis and viewpoint integration. This approach enables us to avoid computationally intensive image analysis tasks associated with traditional image orientation, while allowing us to triangulate numerous images by having them pointed towards the crowdsourced toponym location. The article presents our approach and demonstrates its performance using a real‐world wildfire event as a representative application case study. 相似文献
908.
Peacock EE Hampson GR Nelson RK Xu L Frysinger GS Gaines RB Farrington JW Tripp BW Reddy CM 《Marine pollution bulletin》2007,54(2):214-225
Petroleum hydrocarbons persist in salt marsh sediments in Winsor Cove (Buzzards Bay, Massachusetts) impacted from the 1974 spill of No. 2 fuel oil by the barge Bouchard 65. Intertidal sediment cores were collected from 2001 to 2005 and analyzed for total petroleum hydrocarbons (TPHs). TPHs content was greatest (as high as 8.7 mg g(-1) dry weight) in the surface sediments and decreased with distance landward. Select samples were analyzed for polycyclic aromatic hydrocarbons (PAHs) with values as high as 16.7 microg g(-1) for total naphthalenes and phenanthrenes/anthracenes. These remaining PAHs are mainly C(4)-naphthalenes and C(1)-, C(2)-, and C(3)-phenanthrenes/anthracenes revealing preferential loss of almost all of the naphthalenes and the parent compound phenanthrene. Inspection of the data indicates that biodegradation, water-washing and evaporation were major removal processes for many of the petroleum hydrocarbons in the marsh sediments. In addition, historical data and photographs combined with their recent counterparts indicate that erosion has physically removed these contaminants from this site. 相似文献
909.
Modeling effects of multinode wells on solute transport 总被引:1,自引:0,他引:1
Long-screen wells or long open boreholes with intraborehole flow potentially provide pathways for contaminants to move from one location to another in a ground water flow system. Such wells also can perturb a flow field so that the well will not provide water samples that are representative of ground water quality a short distance away from the well. A methodology is presented to accurately and efficiently simulate solute transport in ground water systems that include wells longer than the grid spacing used in a simulation model of the system and hence are connected to multiple nodes of the grid. The methods are implemented in a MODFLOW-compatible solute-transport model and use MODFLOW's Multi-Node Well Package but are generic and can be readily implemented in other solute-transport models. For nonpumping multinode wells (used to simulate open boreholes or observation wells, for example) and for low-rate pumping wells (in which the flow between the well and the ground water system is not unidirectional), a simple routing and local mixing model was developed to calculate nodal concentrations within the borehole. For high-rate pumping multinode wells (either withdrawal or injection, in which flow between the well and the ground water system is in the same direction at all well nodes), complete and instantaneous mixing in the wellbore of all inflows is assumed. 相似文献
910.